Sounds like they made the fatal error of believing their own propaganda ...
"It's hard to imagine what the Pentagon was thinking when it told the American Army and Marine replacement divisions bound for Iraq earlier this year to leave their tanks and other heavily armored vehicles behind. American military planners seem to have ignored evidence that armed resistance to the occupation was far from suppressed. As a result, they failed to anticipate the kinds of ambushes and urban firefights these troops are now caught up in and against which tanks and armored personnel carriers afford the best protection.
That costly miscalculation has left American soldiers in their thin-skinned Humvees nearly defenseless against the rocket-propelled grenades, roadside bombs and AK-47 rifle fire they face almost daily. While political spokesmen have played down the seriousness of the fighting that has killed 126 Americans just this month, field commanders have been pleading desperately for more armor.
This week, the Pentagon finally ordered that thousands of armored vehicles be sent to Iraq, from 70-ton Abrams tanks to lighter and faster Bradley and Stryker combat vehicles, plus an armored version of the Humvee, whose production is now being accelerated. Every effort must be made to speed the movement of this badly needed equipment to minimize future American casualties.
The Defense Department now tries to justify its earlier mistake of leaving the heavy armor behind by arguing that tankbound soldiers are poorly suited to engaging with the Iraqi civilian population and winning hearts and minds. True enough, but having the tanks on hand would not have prevented such efforts in more secure areas, and would have saved lives in battle zones like Falluja and Najaf.